Electric furnaces for porcelain work : appliances and materials for the making of porcelain inlays ... manufactured by the S.S. White Dental Mfg. Co.

  • S.S. White Dental Manufacturing Company.
Date:
1912
Catalogue details

Licence: In copyright

Credit: Electric furnaces for porcelain work : appliances and materials for the making of porcelain inlays ... manufactured by the S.S. White Dental Mfg. Co. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

    10/40 (page 6)
    The Rheostat For regulating the heat a Rheostat is provided, governed by a control lever, working over a n of thirteen contacts. This unusually large number of contacts permits of more gradual incree or decrease of muffle temperature and makes a close register of the heat possible, an especially jefn] feature when the Pyrometer is used. The resistance wires are imbedded in enamel, assuring beii protection from the effects of climatic changes. Therefore the Furnace is as long-lived in the ipicj as in the driest climate. The 220 Volt Furnace is provided with an additional resistance the base of the furnace, described on page 8. Fig. 4 Fyrometer Muffle, showing Thermo- couple for Attached Pyrometer The Muffle The Muffle is of double construction, an outer envelope inclosing the inner Muffle proper, whic car- ries the heat wires. A fire-clay door is used to close the opening. Both units are of a specially : rac- tory composition and they are held together by refractory fillings and plugs, a thin, tight-fitting teel jacket inclosing the whole. The heat wires pass around and around the inner Muffle, imbedded thin its substance deep enough to avoid accidental short-circuiting, but not so deep as to interfere villi the free radiation of heat into the chamber. There is thus a uniform temperature throughor the chamber, easily regulated to the porcelain used. Electric connection is made automatically by ring contacts upon the muffle in position. (See Fig. 3.) The Muffle is equipped with a Thermo-Couple (see Fig. 4), the wires of which extend from ne; the center of the heat chamber through the rear end of the Muffle, where they are flattened to f<jn a contact for the extension wires of the Pyrometer Indicator. I